The objective is to understand the role of the mechanical (fluid-elastic) activity of the cochlea in the transformation of sound into receptor cell stimulation. The results recently obtained include a determination from an experimental model of the properties of the fluid flow around the outer hair cell cilia and the development of an extended WKB solution for a more realistic model of the gross basilar membrane response including three-dimensional fluid motion. The 3-D model shows much sharper decay of the traveling forces on the inner hair cell cilia has been hampered by a lack of knowledge of the mechanical properties of the components of the Organ of Corti and the supporting structure. Thus the first half of the proposed continuation of effort will be devoted to a repetition and extension of the static point load measurements of Bekesy. The change in properties from fresh to several days post mortem will be obtained. An attempt will be made to obtain the (visco-elastic) changes with frequency, particularly for the tectorial membrane. The main study will be with guinea pig and rat, with later possible consideration of the more unusual horseshoe bat, domestic pig, mountain beaver, and alligator lizard cochlea. Following the completion of these measurements, more solidly based mathematical studies of normal and pathological receptor cell stimulation will be carried out.